STP843

    Problems in the Use of Closed Chambers for Measuring Photosynthesis by a Lotic Macrophyte

    Published: Jan 1984


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    Abstract

    Photosynthesis by Podostemum ceratophyllum in closed production chambers became inhibited by oxygen accumulation and carbon depletion during field investigations. Carbon-14 uptake by this plant during 180-min experiments was initially rapid, then decreased abruptly. The photosynthetic response corresponded to increased oxygen concentration of the chamber water and increased excretion of labelled organic carbon from the plants. Photosynthesis was probably further inhibited by inorganic carbon depletion since this plant is unable to use HCO3 as a carbon source. Alkalinity and pH in the chambers decreased and increased, respectively, reflecting this depletion of available carbon dioxide. These data suggest that use of sealed chambers for aquatic macrophyte production studies may seriously underestimate actual production.

    Keywords:

    photosynthesis, carbon-14, oxygen, inhibition, aquatic macrophytes, primary production, production chambers, HCO, 3, −, utilization, carbon dioxide depletion


    Author Information:

    Hill, BH
    Assistant professor of environmental sciences, University of Texas at Dallas, Richardson, TX

    Webster, JR
    Associate professor of zoology and associate professor of botany, Virginia Polytechnic Institute and State University, Blacksburg, VA

    Linkins, AE
    Associate professor of zoology and associate professor of botany, Virginia Polytechnic Institute and State University, Blacksburg, VA


    Paper ID: STP35225S

    Committee/Subcommittee: D19.24

    DOI: 10.1520/STP35225S


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